Roll-pitch-roll surgical tool

ABSTRACT

A robotic surgical tool includes an elongate shaft having a working end and a shaft axis, and a pair of linking arms each having a proximal end and a distal end. The proximal end is pivotally mounted on the working end of the shaft to rotate around a first pitch axis to produce rotation in first pitch. A wrist member has a proximal portion pivotally connected to the distal end of the linking arm to rotate around a second pitch axis to produce rotation in second pitch. An end effector is pivotally mounted on a distal portion of the wrist member to rotate around a wrist axis of the wrist member to produce rotation in distal roll. The wrist axis extends between the proximal portion and the distal portion of the wrist member. The elongate shaft is rotatable around the shaft axis to produce rotation in proximal roll. At about 90° pitch, the wrist axis is generally perpendicular to the shaft axis. The proximal roll around the shaft axis and the distal roll around the wrist axis do not overlap. The use of the linking arms allows the end effector to be bent back beyond 90° pitch. The ability to operate the end effector at about 90° pitch and to bend back the end effector renders the wrist mechanism more versatile and adaptable to accessing hard to reach locations, particularly with small entry points such as those involving spinal, neural, or rectal surgical sites.

This application is a division of U.S. patent application Ser. No.11/101,375, filed Apr. 6, 2005; which is a continuation of U.S. patentapplication Ser. No. 10/752,934, filed Jan. 6, 2004, now U.S. Pat. No.6,902,560; which is a division of U.S. application Ser. No. 10/340,129filed Jan. 10, 2003, now U.S. Pat. No. 6,685,698; which is a division ofSer. No. 09/626,527, filed Jul. 27, 2000, now U.S. Pat. No. 6,746,443;the full disclosure of which is hereby incorporated by reference for allpurposes

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is related to the following patents and patentapplications, the full disclosures of which are incorporated herein byreference: PCT International Application No. PCT/US98/19508, entitled“Robotic Apparatus”, filed on Sep. 18, 1998, U.S. application Ser. No.09/418,726, entitled “Surgical Robotic Tools, Data Architecture, andUse”, filed on Oct. 15, 1999; U.S. Application Ser. No. 60/111,711,entitled “Image Shifting for a Telerobotic System”, filed on Dec. 8,1998; U.S. application Ser. No. 09/378,173, entitled “Stereo ImagingSystem for Use in Telerobotic System”, filed on Aug. 20, 1999; U.S.application Ser. No. 09/398,507, entitled “Master Having RedundantDegrees of Freedom”, filed on Sep. 17, 1999, U.S. application Ser. No.09/399,457, entitled “Cooperative Minimally Invasive TelesurgerySystem”, filed on Sep. 17, 1999; U.S. application Ser. No. 09/373,678,entitled “Camera Referenced Control in a Minimally Invasive SurgicalApparatus”, filed on Aug. 13, 1999; U.S. Provisional application Ser.No. 09/398,958, entitled “Surgical Tools for Use in Minimally InvasiveTelesurgical Applications”, filed on Sep. 17, 1999; and U.S. Pat. No.5,808,665, entitled “Endoscopic Surgical Instrument and Method for Use”,issued on Sep. 15, 1998.

BACKGROUND OF THE INVENTION

Advances in minimally invasive surgical technology could dramaticallyincrease the number of surgeries performed in a minimally invasivemanner. Minimally invasive medical techniques are aimed at reducing theamount of extraneous tissue that is damaged during diagnostic orsurgical procedures, thereby reducing patient recovery time, discomfort,and deleterious side effects. The average length of a hospital stay fora standard surgery may also be shortened significantly using minimallyinvasive surgical techniques. Thus, an increased adoption of minimallyinvasive techniques could save millions of hospital days, and millionsof dollars annually in hospital residency costs alone. Patient recoverytimes, patient discomfort, surgical side effects, and time away fromwork may also be reduced with minimally invasive surgery.

The most common form of minimally invasive surgery may be endoscopy.Probably the most common form of endoscopy is laparoscopy, which isminimally invasive inspection and surgery inside the abdominal cavity.In standard laparoscopic surgery, a patient's abdomen is insufflatedwith gas, and cannula sleeves are passed through small (approximately ½inch) incisions to provide entry ports for laparoscopic surgicalinstruments. The laparoscopic surgical instruments generally include alaparoscope (for viewing the surgical field) and working tools. Theworking tools are similar to those used in conventional (open) surgery,except that the working end or end effector of each tool is separatedfrom its handle by an extension tube. As used herein, the term “endeffector” means the actual working part of the surgical instrument andcan include clamps, graspers, scissors, staplers, and needle holders,for example. To perform surgical procedures, the surgeon passes theseworking tools or instruments through the cannula sleeves to an internalsurgical site and manipulates them from outside the abdomen. The surgeonmonitors the procedure by means of a monitor that displays an image ofthe surgical site taken from the laparoscope. Similar endoscopictechniques are employed in, e.g., arthroscopy, retroperitoneoscopy,pelviscopy, nephroscopy, cystoscopy, cisternoscopy, sinoscopy,hysteroscopy, urethroscopy and the like.

There are many disadvantages relating to current minimally invasivesurgical (MIS) technology. For example, existing MIS instruments denythe surgeon the flexibility of tool placement found in open surgery.Most current laparoscopic tools have rigid shafts, so that it can bedifficult to approach the worksite through the small incisionAdditionally, the length and construction of many endoscopic instrumentsreduces the surgeon's ability to feel forces exerted by tissues andorgans on the end effector of the associated tool. The lack of dexterityand sensitivity of endoscopic tools is a major impediment to theexpansion of minimally invasive surgery.

Minimally invasive telesurgical robotic systems are being developed toincrease a surgeon's dexterity when working within an internal surgicalsite, as well as to allow a surgeon to operate on a patient from aremote location. In a telesurgery system, the surgeon is often providedwith an image of the surgical site at a computer workstation. Whileviewing a three-dimensional image of the surgical site on a suitableviewer or display, the surgeon performs the surgical procedures on thepatient by manipulating master input or control devices of theworkstation. The master controls the motion of a servomechanicallyoperated surgical instrument. During the surgical procedure, thetelesurgical system can provide mechanical actuation and control of avariety of surgical instruments or tools having end effectors such as,e.g., tissue graspers, needle drivers, or the like, that perform variousfunctions for the surgeon, e.g., holding or driving a needle, grasping ablood vessel, or dissecting tissue, or the like, in response tomanipulation of the master control devices.

Some surgical tools employ a roll-pitch-yaw mechanism for providingthree degrees of rotational movement to an end effector around threeperpendicular axes. At about 90° pitch, the yaw and roll rotationalmovements overlap, resulting in the loss of one degree of rotationalmovement.

SUMMARY OF THE INVENTION

The present invention is generally directed to robotic surgery methods,devices, and systems. The invention provides a minimally invasivesurgical tool which operates with three degrees of rotational movementat about 90° pitch. In particular, the surgical tool employs aroll-pitch-roll configuration in which an elongate shaft is rotatable inproximal roll, a wrist member is pivotally mounted on the working end ofthe elongate shaft to rotate in pitch, and an end effector is pivotallymounted on the wrist member to rotate in distal roll around the wristaxis of the wrist member. At about 90° pitch, the wrist axis isgenerally perpendicular to the shaft axis of the elongate shaft. Theproximal roll around the shaft axis and the distal roll around the wristaxis do not overlap. In some embodiments, a pulley and cable mechanismis used to rotate and actuate the end effector.

In some embodiments, the end effector can be bent back beyond 90° pitch.The mechanism coupling the end effector to the working end of theelongate shaft allows the wrist member and end effector to bend back byan angle θ of more than about 90° from the forward position, desirablyby more than about 120°, and more desirably by more than about 135°. Theability to operate the end effector at about 90° pitch and to bend backthe end effector renders the wrist mechanism more versatile andadaptable to accessing hard to reach locations, particularly with smallentry points such as those involving spinal, neural, or rectal surgicalsites. In specific embodiments, a pair of linking arms are pivotallyconnected between the working end and the wrist member to facilitatebend back pitching while maintaining the size of the tool to asufficiently small size for minimally invasive surgical applications.

In accordance to an aspect of the present invention, a minimallyinvasive surgical instrument comprises an elongate shaft having aworking end and a shaft axis, and at least one linking arm having aproximal end and a distal end. The proximal end is pivotally mounted onthe working end of the shaft to rotate around a first pitch axis whichis nonparallel to the shaft axis. A wrist member has a proximal portionpivotally connected to the distal end of the linking arm to rotatearound a second pitch axis which is nonparallel to the shaft axis. Anend effector is pivotally mounted on a distal portion of the wristmember to rotate around a wrist axis of the wrist member. The wrist axisextends between the proximal portion and the distal portion of the wristmember. The elongate shaft is rotatable around the shaft axis.

In some embodiments, the first pitch axis and the second pitch axis areparallel, and are perpendicular to the shaft axis. A pair of linkingarms are connected between the working end and the wrist member. The endeffector includes an end effector support pivotally mounted on thedistal portion of the wrist member to rotate around the wrist axis. Theend effector includes at least one end effector link pivotally mountedon the end effector support to rotate around a pivot axis which isnonparallel to the wrist axis. The pivot axis may be perpendicular tothe wrist axis. The end effector may include a pair of end effectorlinks. The end effector links may be rotatable around the pivot axis tomove toward and away from one another. The end effector links may berotatable around the pivot axis to move together in the same direction.One of the end effector links may be fixed relative to the end effectorsupport.

In accordance with another aspect of the invention, a minimally invasivesurgical instrument comprises an elongate shaft having a working end anda proximal end. The elongate shaft has a shaft axis between the proximalend and the working end. A wrist member includes a wrist axis between aproximal portion and a distal portion. An end effector is pivotallymounted on the distal portion of the wrist member to rotate around thewrist axis. At least one linking member is rotatably coupled between theworking end and the wrist member to permit rotation of the wrist memberrelative to the working end, from a forward position in which the wristaxis is oriented with the end effector at the distal portion pointinggenerally away from the proximal end of the elongate shaft, to abackward position in which the wrist axis is oriented with the endeffector at the distal portion pointing generally toward the proximalend of the elongate shaft.

In accordance with another aspect of the present invention, a method ofperforming minimally invasive surgery in a body cavity of a patientcomprises introducing an elongate shaft having a working end into thecavity. The elongate shaft has a proximal end and a shaft axis betweenthe working end and the proximal end. A wrist member which is pivotallycoupled with the working end is rotated relative to the working end. Thewrist member having a wrist axis. The method further comprises rotatingat least one of the elongate shaft around the shaft axis and an endeffector pivotally mounted on the wrist member around the wrist axis toposition the end effector at a desired location inside the cavity.

In some embodiments, the wrist member is rotated around a pitch axiswhich is perpendicular to at least one of the shaft axis and the wristaxis to change an angle between the wrist axis and the shaft axis. Thewrist member is rotated relative to the working end until the wrist axisis approximately perpendicular to the shaft axis. The wrist member maybe rotated relative to the working end from a forward position in whichthe wrist axis is oriented with the end effector pointing generally awayfrom the proximal end of the elongate shaft, to a backward position inwhich the wrist axis is oriented with the end effector pointinggenerally toward the proximal end of the elongate shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a robotic arm and surgical instrument assemblyaccording to a preferred embodiment of the invention;

FIG. 2 is a perspective view of the robotic arm and surgical instrumentassembly of FIG. 1;

FIG. 3 is a perspective view of a surgical instrument according to apreferred embodiment of the invention;

FIG. 4 is a schematic kinematic diagram corresponding to the side viewof the robotic arm shown in FIG. 1, and indicates the arm having beendisplaced from one position into another position;

FIG. 5 is a perspective view of a roll-pitch-yaw wrist mechanism;

FIG. 6 is a front view of the wrist mechanism of FIG. 5 along arrow VI;

FIG. 7 is a side view of the wrist mechanism of FIG. 5 along arrow VII;

FIG. 8 is a perspective view of the wrist mechanism of FIG. 5schematically illustrating the singularity at the 90° pitch position;

FIG. 9 is a perspective view of a roll-pitch-roll wrist mechanismaccording to a preferred embodiment of the present invention;

FIG. 10 is a front view of the wrist mechanism of FIG. 9 along arrow X;

FIG. 11 is a side view of the wrist mechanism of FIG. 9 along arrow XI;

FIG. 12 is a perspective view of the wrist mechanism of FIG. 9 at the90° pitch position;

FIG. 13 is a perspective view of a roll-pitch-roll wrist mechanismaccording to another preferred embodiment of the present invention;

FIG. 14 is a sectional view of the wrist mechanism of FIG. 13 alongXIV-XIV;

FIG. 15 is another perspective view of the wrist mechanism of FIG. 13;

FIG. 16 is another perspective view of the wrist mechanism of FIG. 13;and

FIG. 17 is a perspective view of the wrist mechanism of FIG. 13schematically illustrating the bend back feature of the end effector.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 illustrate a robotic arm and surgical instrument assembly10. The assembly 10 includes a robotic arm 12 and a surgical instrument14. FIG. 3 indicates the general appearance of the surgical instrument14.

The surgical instrument 14 includes an elongate shaft 14.1. A wrist-likemechanism 50 is located at a working end of the shaft 14.1. A housing 53arranged releasably to couple the instrument 14 to the robotic arm 12 islocated at an opposed end of the shaft 14.1. In FIG. 1, and when theinstrument 14 is coupled or mounted on the robotic arm 12, the shaft14.1 extends along an axis indicated at 14.2. The instrument 14 istypically releasably mounted on a carriage 11 which is driven totranslate along a linear guide formation 24 in the direction of arrowsP. The surgical instrument 14 is described in greater detail hereinbelow.

The robotic arm 12 is typically mounted on a base (not shown) by abracket or mounting plate 16. The base is typically in the form of amobile cart or trolley (not shown) which is retained in a stationaryposition during a surgical procedure.

The robotic arm 12 includes a cradle 18, an upper arm portion 20, aforearm portion 22, and the guide formation 24. The cradle 18 ispivotally mounted on the plate 16 in a gimbaled fashion to permitrocking movement of the cradle in the direction of arrows 26 about apivot axis 28, as shown in FIG. 2. The upper arm portion 20 includeslink members 30, 32 and the forearm portion 22 includes link members 34,36. The link members 30, 32 are pivotally mounted on the cradle 18 andare pivotally connected to the link members 34, 36. The link members 34,36 are pivotally connected to the guide formation 24. The pivotalconnections between the link members 30, 32, 34, 36, the cradle 18, andthe guide formation 24 are arranged to enable the robotic arm to move ina specific manner.

The movements of the robotic arm 12 is illustrated schematically in FIG.4. The solid lines schematically indicate one position of the roboticarm and the dashed lines indicate another possible position into whichthe arm can be displaced from the position indicated in solid lines.

It will be understood that in a preferred embodiment, the axis 14.2along which the shaft 14.1 of the instrument 14 extends when mounted onthe robotic arm 12 pivots about a pivot center or fulcrum 49. Thus,irrespective of the movement of the robotic arm 12, the pivot center 49normally remains in substantially the same position relative to thestationary cart 300 on which the arm 12 is mounted. In use, the pivotcenter 49 is typically positioned at a port of entry into a patient'sbody during an endoscopic procedure when an internal surgical procedureis to be performed. It will be appreciated that the shaft 14.1 extendsthrough such a port of entry, the wrist-like mechanism 50 then beingpositioned inside the patient's body. Thus, the general position of themechanism 50 relative to the surgical site in a patient's body can bechanged by movement of the arm 12. Since the pivot center 49 iscoincident with the port of entry, such movement of the arm does notexcessively effect the surrounding tissue at the port of entry. It is tobe appreciated that the field of application of the invention is notlimited to surgical procedures at internal surgical sites only, but canbe used on open surgical sites as well.

As can best be seen in FIG. 4, the robotic arm 12 provides three degreesof freedom of movement to the surgical instrument 14 when mountedthereon. These degrees of freedom of movement are firstly the gimbaledmotion indicated by arrows 26, pivoting or pitching movement asindicated by arrows 27, and the linear displacement in the direction ofarrows P. Movement of the arm as indicated by arrows 26, 27 and P iscontrolled by appropriately positioned actuators, e.g., electricalmotors or the like, which respond to inputs from its associated mastercontrol to drive the arm 12 to a desired position as dictated bymovement of the master control.

Roll-Pitch-Yaw Mechanism

FIGS. 5, 6 and 7 show a roll-pitch-yaw wrist-like mechanism 50. In FIG.5, the working end of the shaft 14.1 is indicated at 14.3. Thewrist-like mechanism 50 includes a rigid wrist member 52. One endportion of the wrist member 52 is pivotally mounted in a clevis 17 onthe end 14.3 of the shaft 14.1 by means of a pivotal connection 54. Asbest seen in FIG. 7, the wrist member 52 can pitch in the direction ofarrows 56 about the pivotal connection 54. This rotation around thepivotal connection 54 in the direction 56 is referred to as the pivot orpitch of the wrist member 52. The end 14.3 is rotatable with the shaft14.1 around the axis 14.2 in the direction H, as shown in FIGS. 3 and 5.This rotation around the axis 14.2 in the direction H is referred to asthe roll of the working end 14.3.

An end effector, generally indicated by reference numeral 58, ispivotally mounted on an opposed end of the wrist member 52. The endeffector 58 is in the form of forceps or graspers for grasping tissue orthe like during a surgical procedure. Accordingly, the end effector 58has two parts 58.1, 58.2 together defining a jaw-like arrangement. Theend effector 58 is pivotally mounted in a clevis 19 on an opposed end ofthe wrist member 52, by means of a pivotal connection 60. Free ends 11,13 of the parts 58.1, 58.2 are angularly displaceable about the pivotalconnection 60 toward and away from each other as indicated by arrows 62,63 in FIG. 6. This movement of the parts 58.1, 58.2 is referred to asthe grip of the end effector 58. The members 58.1, 58.2 can be displacedangularly about the pivotal connection 60 to change the orientation ofthe end effector 58 as a whole, relative to the wrist member 52. Thus,each part 58.1, 58.2 is angularly displaceable about the pivotalconnection 60 independently of the other, so that the end effector 58is, as a whole, angularly displaceable about the pivotal connection 60in the direction 61, as indicated in dashed lines in FIG. 6. Thisrotation around the pivotal connection 60 in the direction 61 isreferred to the yaw of the end effector 58. The wrist mechanism 50 asillustrated in FIGS. 5-7 is referred to as a roll-pitch-yaw mechanismhaving roll in the direction H, pitch in the direction 56, and yaw inthe direction 61.

The parts 58.1, 58.2 each include an elongate finger portion or endeffector element 58.3 and an end effector mounting formation in the formof, e.g., a pulley portion 58.5. In a preferred embodiment, the fingerportion 58.3 is integrally formed with the pulley portion 58.5. Thepulley portion 58.5 defines a circumferentially extending channel 58.6in which an elongate element in the form of e.g., an activation cable,is carried. A generally circumferentially directed hole 58.8 extendsthrough a nape region of the finger portion 58.3 and generally inregister with the circumferentially extending channel 58.6. The hole58.8 has a first portion 58.9 and a second portion 58.10 having adiameter greater than the first portion 58.9. In use, the activationcable has a thickened portion along its length which seats in the holeportion 58.10, the rest of the activation cable then extending along thechannel 58.6 in opposed directions. The thickened portion is crimped inits seated position in the hole portion 58.10 so as to anchor the cablein the hole 58.8. It will be appreciated that a greater force isnecessary to clamp the free ends together when gripping an objecttherebetween, than that which is required to open the free ends 11, 13.Thus, the thickened portion of the cable is urged against an annularstepped surface between the hole portion 58.9 and the hole portion58.10, when the free ends 11, 13 are urged into a closed condition.

As best seen in FIG. 6, the wrist member 52 is flanked by two sets ofpulleys 64, 66 which are coaxially positioned on the pivotal connection54 and in the clevis 17 at the end 14.3 of the shaft 14.1. Two furthersets of pulleys 68, 70 are rotatably mounted on opposed sides of thewrist member 52. Each pulley of the set of pulleys 68 on the one side ofthe wrist member 52 is generally co-planar with an associated pulley ofthe pulley set 66. Furthermore, each of the pulleys 68 is positionedsuch that its circumference is in close proximity to the circumferenceof its associated pulley of the pulley set 66. A similar arrangementexists for each pulley of the pulley set 70 on the other side of thewrist member and its associated pulley of the pulley set 64. Thus, thecircumferentially extending channel formation of each pulley of thepulley sets 68, 70 and their associated pulleys of the pulley sets 64,66 define between each of them a space 72 through which an activationcable can snugly pass.

A plurality of elongate elements, e.g., cables, are used to effectmovement of the wrist mechanism 50 and end effector 58. As seen in FIG.7, two cables C1, C2 are anchored on the parts 58.1, 58.2, respectively,to effect movement of the parts 58.1, 58.2 independently in directions62, 63 or as a whole (FIG. 6).

Cable C1 rides over an outer pulley of the pulley set 64, an outerpulley of the pulley set 70, over part of circumferential channel 58.6of the pulley portion 58.5 of the part 58.2 of the end effector 58,through the hole 58.8, again along part of the circumferential channel58.6 of the pulley portion 58.5, over an outer pulley of the pulley set68 and over an outer pulley of the pulley set 66. Similarly, cable C2rides over an inner pulley of the pulley set 64, over an inner pulley ofthe pulley set 70, along the circumferential channel 58.6 of the part58.1 of the end effector 58, through the hole 58.8 of the part 58.1,again along the circumferential channel 58.6 of the pulley portion 58.5,over an inner pulley of the pulley set 68 and over an inner pulley ofthe pulley set 66. The cables C1, C2 pass from the wrist mechanism 50through appropriately positioned holes 47 in the base region of theclevis 17 (FIG. 5), and internally along the shaft, toward the housing53 (FIG. 3). The housing 53 includes driving members, e.g., in the formof spool assemblies for manipulating the cables. Additional details ofthe spool assemblies and the grip mechanism for manipulating the fingerportions 58.1, 58.2 to achieve gripping as well as description ofvarious surgical tools can be found in U.S. application Ser. No.09/398,958, entitled “Surgical Tools for Use in Minimally InvasiveTelesurgical Applications”, filed on Sep. 17, 1999.

When the end effector 58 is oriented forward, the roll, pitch, and yawprovide rotational movements relative to three generally perpendicularaxes. FIG. 8 shows the position of the end effector 58 after rotation inpitch in the direction 56 of the wrist member 52 around the pivotalconnection 54 by about 90°. In this position, the yaw in the direction61 around the pivotal connection 60 overlaps with the roll H of theworking end 14.3. The overlap or redundancy results in the loss of onedegree of freedom of movement of the end effector 58 at or near thisposition of singularity. In some applications, the end effector 58 maybe used primarily at this position of about 90° pitch, It is desirableto provide a wrist mechanism that does not operate at a singularity inthis position.

Roll-Pitch-Roll Mechanism

FIGS. 9-11 show a roll-pitch-roll wrist-like mechanism 500. In FIG. 9,the working end of the tool shaft is indicated at 502, and includes apair of extensions 506. The wrist-like mechanism 500 includes a rigidwrist member 504. One end portion of the wrist member 504 forms a clevis508 in which the extensions 506 of the working end 502 of the tool shaftis pivotally mounted by means of a pivotal connection 510. As best seenin FIG. 10, the wrist member 504 can pitch in the direction of arrows512 about the pivotal connection 510. This rotation around the pivotalconnection 510 in the direction 512 is referred to as the pivot or pitchof the wrist member 504. The end 502 is rotatable with the tool shaftaround the shaft axis in the direction 516. This rotation around theshaft axis in the direction 516 is referred to as the roll of theworking end 502.

An end effector, generally indicated by reference numeral 514, issupported on an end effector support base 518 which is pivotally mountedon an opposed end of the wrist member 504 to rotate around its axis inthe direction 520 as shown in FIG. 9. In the embodiment shown, the axisof the base 518 coincides with the axis of the wrist member 504. Therotation in the direction 520 is referred to the distal roll of the endeffector 514. This distal roll of the end effector 514 in the direction520 is differentiated from the proximal roll of the working end 502 inthe direction 516. In the position of the wrist mechanism 500 as shownin FIGS. 9-11, the distal roll 520 of the end effector 514 overlaps withthe proximal roll 516 of the working end 502. Because the rotation ofthe wrist member 504 around the pivotal connection 510 provides pitch512 of the end effector 514, the distal roll 520 generally will notcoincide with the proximal roll 516. The wrist mechanism 500 asillustrated in FIGS. 9-11 is referred to as a roll-pitch-roll mechanism.

The end effector 514 is in the form of forceps or graspers for graspingtissue or the like during a surgical procedure. Accordingly, the endeffector 514 has two parts 522.1, 522.2 together defining a jaw-likearrangement. The two parts 522.1, 522.2 are pivotally mounted in aclevis 524 on the base 518, by means of a pivotal connection 526. Freeends 528.1, 528.2 of the parts 522.1, 522.2 are angularly displaceableabout the pivotal connection 526 toward and away from each other asindicated by arrows 530, 532 in FIG. 10. This movement is referred to asthe grip of the end effector 514. The members 522.1, 522.2 can bedisplaced angularly about the pivotal connection 526 to change theorientation of the end effector 514 as a whole, relative to the wristmember 504. Thus, each part 522.1, 522.2 is angularly displaceable aboutthe pivotal connection 526 independently of the other, so that the endeffector 514 is, as a whole, angularly displaceable about the pivotalconnection 526 in the direction 534, as shown in FIG. 10. This rotationaround the pivotal connection 526 is referred to the yaw of the endeffector 514. In the position of the wrist mechanism 500 as shown inFIGS. 9-11, the yaw 534 of the end effector 514 overlaps with the pitch512 of the wrist member 504. Because the rotation of the base 518provides distal roll 520 of the end effector 514, the yaw 534 generallywill not coincide with the pitch 512. With the additional degree offreedom in yaw in the specific embodiment shown, the wrist mechanism 500as illustrated in FIGS. 9-11 may be referred to as a roll-pitch-roll-yawmechanism.

The parts 522.1, 522.2 each include an elongate finger portion or endeffector element 536 and an end effector mounting formation in the formof, e.g., a pulley portion 538. The finger portion 536 may be integrallyformed with the pulley portion 538. The pulley portion 538 defines acircumferentially extending channel for receiving an activation cable ina manner similar to the pulley portion 58.5 in the end effector 58 ofFIGS. 5-7. Two elongate members such as cables C1, C2 are used to effectmovement of the parts 522.1, 522.2 in yaw 534 and grip 530, 532. Thecables C1, C2 pass from the wrist mechanism 500 internally through theshaft toward the housing 53 (FIG. 3). For simplicity, details of thepulley portion 538 in the end effector 514 of FIGS. 9-11 are omitted.The configuration and operation of the parts 522.1, 522.2 are similar tothose of the parts 58.1, 58.2 in FIGS. 5-7.

In an alternate embodiment, the end effector 514 does not include theadditional degree of freedom in yaw 534 but is still configured toperform the grip function. The parts 522.1, 522.2 perform gripping anddoes not move as a whole in yaw For example, one part 522.1 may besubstantially fixed with respect to the support base 518, while theother part 522.2 is rotatable relative to the pivotal connection 526 tomove away from and toward the fixed part 522.1 in grip 530, 532. In thatcase, only one cable C2 is needed to manipulate the part 522.2 to effectthe grip movement thereof (C1 is no longer needed). This alternateroll-pitch-roll mechanism with grip capability is simpler in structureand operation than the roll-pitch-roll-yaw mechanism with grip.

As best seen in FIG. 11, the pair of working end extensions 506 areflanked by two pulleys 540, 542 which are coaxially positioned on thepivotal connection 510 and in the clevis 508 at the proximal end of thewrist member 504. A tangent pulley 544 which is associated with thepulley 540 is attached to the bottom of the end effector support base518. Another tangent pulley 546 which is associated with the pulley 542is also attached to the bottom of the base 518. The tangent pulleys 544,546 in the specific embodiment shown are generally perpendicular to thepair of pulleys 540, 542, and move together with the base 518. Thecircumference of each tangent pulley 544 or 546 is in close proximity tothe circumference of its associated pulley 540 or 542. In a specificembodiment, the tangent pulleys are integrally formed with the bottom ofthe base 518.

Two elongate elements such as cables C3, C4 are used to effect movementof the end effector 514 and support base 518 in distal roll 520. As bestseen in FIG. 11, two cables C3, C4 are anchored on the tangent pulleys544, 546, respectively, to effect distal roll 520 of the base 518attached to the tangent pulleys 544, 546. Cable C3 wraps around aportion of the tangent pulley 544, rides over the pulley 540 and extendsthrough the shaft 14.1 to the housing 53, while cable C4 wraps around aportion of the tangent pulley 546, rides over the pulley 542 and extendsthrough the shaft 14.1 to the housing 53 (FIG. 3). The circumference ofeach tangent pulley 544 or 546 is in sufficiently close proximity to thecircumference of its associated pulley 540 or 542 to allow thecorresponding cable C3 or C4 to slide in the pulley channels securelythrough the approximately 90° change in orientation from one pulley tothe other. In a preferred embodiment, cables C3, C4 are connected in thehousing 53 and form a single cable. The single cable substantially doesnot change in length during distal roll 520 so that no tensioning springor similar member is needed.

Another pulley 550 is disposed adjacent the pulley 540 and is coaxiallypositioned with the pulleys 540, 542 on the pivotal connection 510 andin the clevis 508 at the proximal end of the wrist member 504. Anelongate element such as cable C5 is used to effect movement of thewrist member 504 in pitch 512. As seen in FIGS. 9-11, cable C5 isanchored on the pulley 550, rides over the pulley 540, and extendsthrough the shaft 14.1 to the housing 53 (FIG. 3). In an alternateembodiment, another pulley is coaxially positioned adjacent the pulley542 opposite from the pulley 550 on the other side of the pair ofworking end extensions 506, and the opposite end of cable C5 is anchoredon that pulley. In the alternate embodiment, cable C5 substantially doesnot change in length during pitch 512 of the wrist member 504 so that notensioning spring or similar member is needed.

FIG. 12 shows the position of the end effector 514 after rotation inpitch 512 of the wrist member 504 around the pivotal connection 510 byabout 90°. In this position, there is no overlap among the proximal roll516, pitch 512, and distal roll 520, which are oriented around axes thatare generally perpendicular to each other, making the wrist mechanism500 more suitable to operate in the 90° pitch position than the wristmechanism 50 of FIGS. 5-8. In addition, the two parts 522.1, 522.2 ofthe end effector 514 are movable in yaw 524 and in grip 530, 532 in thespecific embodiment shown. In the forward position of the end effector514 as shown in FIGS. 9-11, the distal roll 520 coincides with theproximal roll 516, which presents a singularity. The addition of the yaw524 of the end effector 514 in conjunction with the distal roll 520 in apreferred embodiment essentially eliminates the singularity by providingroll 516, pitch 512, and yaw 534 oriented around axes that arenonparallel and may be generally perpendicular to each other.

Bend Back Roll-Pitch-Roll Mechanism

FIGS. 13-17 show a roll-pitch-roll wrist-like mechanism 560 including abend back feature in the pitch direction to increase the versatility ofthe mechanism 560. In FIG. 13, the working end of the tool shaft isindicated at 562. The end 562 is rotatable with the tool shaft aroundthe shaft axis in the proximal roll 563. The wrist-like mechanism 560includes a rigid wrist member 564. The working end 562 forms a workingend clevis 566, and one end portion of the wrist member 564 forms awrist member clevis 568 facing the clevis 566. The working end 562includes a central extension 570. Disposed in the working end clevis 566are a first pair of pitch or knee pulleys 572, 574 on opposite sides ofthe central extension 570. The pulleys 572, 574 are coaxially positionedon a pivotal connection 575. A central extension 576 is located in thewrist member clevis 568. Disposed in the wrist member clevis 568 are asecond pair of pitch or knee pulleys 578, 580 on opposite sides of thecentral extension 576. The pulleys 578, 580 are coaxially positioned ona pivotal connection 581. The second pair of pitch pulleys 578, 580 inthe wrist member clevis 568 are coplanar with the first pair of pitchpulleys 572, 574 in the working end clevis 566, respectively.

As best seen in FIGS. 13 and 14, a first pair of distal roll pulleys584, 586 are disposed in the working end clevis 566 on opposite sides ofthe central extension 570. The pulleys 584, 586 are coaxially positionedon the pivotal connection 575. A second pair of distal roll pulleys 588,590 are disposed in the wrist member clevis 568 on opposite sides of thecentral extension 576. The pulleys 588, 590 are coaxially positioned onthe pivotal connection 581. The second pair of distal roll pulleys 588,590 in the wrist member clevis 568 are coplanar with the first pair ofdistal roll pulleys 584, 586 in the working end clevis 566,respectively.

A pair of bend back pulley arms or lining arms 592, 594 extend betweenthe working end clevis 566 and the wrist member clevis 568, and aredisposed on opposite sides of the central extensions 570, 576. Eachpulley arm 592, 594 has an end coaxially positioned on the pivotalconnection 575 of the working end 562 and another end coaxiallypositioned on the pivotal connection 581 of the wrist member 564.Rotation of the bend back pulley arms 592, 594 relative to the workingend 562 around the pivotal connection 575 in the direction 596 providesproximal pitch, while rotation of the wrist member 564 relative to thebend back pulley arms 592, 594 around the pivotal connection 581 in thedirection 598 provides distal pitch. The proximal pitch 596 and distalpitch 598 allow the wrist member 564 to be bent back in pitch by morethan 90° as discussed in more detail below.

The central extension 576 in the wrist member clevis 568 is connected toa support base 602 for an end effector, generally indicated by referencenumeral 600. The central extension 576 may be integrally formed with thebase 602. The support base 602 is pivotally mounted on an opposed end ofthe wrist member 564 to rotate around its axis in the direction 604, asshown in FIG. 13. In the embodiment shown, the axis of the base 602coincides with the wrist axis of the wrist member 564. The rotation inthe direction 604 is referred to the distal roll of the end effector600. This distal roll of the end effector 600 in the direction 604 isdifferentiated from the proximal roll of the working end 562 in thedirection 563. In the position of the wrist mechanism 560 as shown inFIGS. 13-16, the distal roll 604 of the end effector 600 coincides withthe proximal roll 563 of the working end 562. Because the rotation ofthe wrist member 564 around the pivotal connections 575, 581 providescompound pitch 596, 598 of the end effector 600, the distal roll 604generally will not coincide with the proximal roll 563. The wristmechanism 560 as illustrated in FIGS. 13-17 is referred to as a bendback roll-pitch-roll mechanism.

The end effector 600 is in the form of forceps or graspers for graspingtissue or the like during a surgical procedure. Accordingly, the endeffector 600 has two parts 608.1, 608.2 together defining a jaw-likearrangement. The two parts 608.1, 608.2 are pivotally mounted in aclevis 610 on the base 602, by means of a pivotal connection 612.Although free ends 614.1, 614.2 of the parts 608.1, 608.2 may beangularly displaceable about the pivotal connection 612 toward and awayfrom each other in some embodiments, the specific embodiment shown inFIGS. 13-17 permits rotation of only the part 608.2 relative to thepivotal connection 612. The other part 608.1 is fixed relative to thebase 602. The movable part 608.2 is movable toward and away from thefixed part 608.1 as indicated by arrows 616, 618 in FIG. 16, Thismovement is referred to as the grip of the end effector 600.

The movable part 608.2 includes a mounting formation in the form of,e.g., a pulley portion 620. The pulley portion 620 defines acircumferentially extending channel for receiving an elongate membersuch as an activation cable C1 which is anchored to the pulley portion620, as best seen in FIGS. 13 and 14. The cable C1 pass through thecentral extensions 576, 570 and the shaft toward the housing 53 (FIG.3). In a preferred embodiment, the cable C1 forms a continuous loopbetween the pulley portion 620 and the housing 53 and does not change inlength during grip 616, 618 of the end effector 600, so that notensioning spring is needed.

Two elongate elements such as cables C3, C4 are used to effect movementof the end effector 600 and support base 602 in distal roll 604. As bestseen in FIG. 14, two cables C3, C4 are anchored on the tangent surface624 of the central extension 576 of the base 602 to effect distal roll604 of the base 602 (FIG. 13). Cable C3 wraps around a portion of thetangent surface 624, while cable C4 wraps around another portion of thetangent surface 624. Cable C3 rides over the roll pulleys 588, 584 andextends through the shaft 14.1 to the housing 53, while cable C4 ridesover the roll pulleys 590, 586 and extends through the shaft 14.1 to thehousing 53 (FIG. 3). The circumference of the tangent surface 624 is insufficiently close proximity to the circumferences of the two rollpulleys 588, 590 to allow the corresponding cables C3, C4, respectively,to slide in the pulley channels securely through the approximately 90°change in orientation from the roll pulleys 588, 590 to the tangentsurface 624. In a preferred embodiment, cables C3, C4 are connected inthe housing 53 and form a single cable. The single cable substantiallydoes not change in length during distal roll 604 so that no tensioningspring or similar member is needed. For clarity, cables C3, C4 are notshown in FIGS. 13 and 15-17. In an alternate embodiment, the tangentsurface 624 may include a pair of circumferential channels for receivingthe cables C3, C4 such as those for the tangent pulleys 544, 546 shownin FIG. 11 for the wrist mechanism 500.

As best seen in FIG. 14, two cables C5, C6 are provided for activatingroll 596, 598 of the wrist member 564. Cable C5 is anchored on thepulley 578, rides over the pulleys 578, 572, and extends through theshaft 14.1 to the housing 53 (FIG. 3). Cable C6 is anchored on thepulley 580, rides over the pulleys 580, 574, and extends through theshaft 14.1 to the housing 53. In a preferred embodiment, the two cablesC5, C6 are connected to form a single cable that substantially does notchange in length during pitch 596, 598 of the wrist member 564 so thatno tensioning spring is needed.

FIG. 17 illustrates the bend back feature of the wrist mechanism 560.The compound pitch 596, 598 around pivotal connections 575, 581 allowsthe wrist member 564 and end effector 600 to bend back by an angle θ ofmore than about 90° from the forward position of FIGS. 13-16, desirablyby more than about 120°, and more desirably by more than about 135°.Thus, the angle between the shaft axis and the wrist axis is about 180°when the end effector 600 is in the forward position, and is less than90° in the bent back position, and may be down to less than about 60° orless than about 45°. The ability to bend back the end effector 600renders the wrist mechanism 560 more versatile and adaptable toaccessing hard to reach locations, particularly with small entry pointssuch as those involving spinal, neural, or rectal surgical sites. Theuse of the linking arms 592, 594 provides this capability whilemaintaining the size of the tool 560 to a sufficiently small size forminimally invasive surgical applications.

The above-described arrangements of apparatus and methods are merelyillustrative of applications of the principles of this invention andmany other embodiments and modifications may be made without departingfrom the spirit and scope of the invention as defined in the claims. Forinstance, the linking arms may have other configurations. Differentactuation mechanisms other than activating cables may be used tomanipulate the wrist member and end effector. The scope of the inventionshould, therefore, be determined not with reference to the abovedescription, but instead should be determined with reference to theappended claims along with their full scope of equivalents.

1-11. (canceled)
 12. A method for minimally invasive surgery comprisingproviding: a tool shaft having a proximal end and a working end; a wristmember having a proximal end and a distal end, the proximal end of thewrist member coupled to the distal end of the support member by apivotal connection defining a pitch axis; a base coupled to the distalend of the wrist member, the base supporting an end effector; first andsecond pulleys coaxially positioned on the pitch axis; first and secondtangent surfaces attached to the bottom of the base, the first andsecond tangent surfaces sharing a distal roll axis perpendicular to thepitch axis; a first elongate element engaging the first tangent surfaceand the first pulley, an end of the first elongate element runningthrough the tool shaft; and a second elongate element engaging thesecond tangent surface and the second pulley, an end of the secondelongate element running through the tool shaft; the method furthercomprising pulling the first elongate element to rotate the base in afirst direction, and pulling the second elongate element to rotate thebase in a second direction opposite the first direction.
 13. The methodof claim 12, further comprising providing: a pitch pulley fixed to thepivotal connection defining the pitch axis, and a pitch elongate elementengaging the pitch pulley, the pitch elongate element running throughthe wrist member through the tool shaft; a first and second partpivotally mounted on the base by a pivotal connection defining a yawaxis, the first and second parts each comprising a pulley portionmounted coaxially on the pivotal connection defining the yaw axis; thirdand fourth elongate elements coupled with the pulley portions of thefirst and second parts, respectively, the third and fourth elongateelements running through the wrist member through the tool shaft; themethod further comprising: pulling the third and fourth elongateelements to rotate the first and second parts, respectively, about thepitch axis.
 14. A method for minimally invasive surgery comprisingproviding: a tool shaft having a proximal end and a working end; a wristmember having a proximal end and a distal end; a base coupled to thedistal end of the wrist member, the base supporting an end effector; afirst arm linking the working end of the tool shaft with the proximalend of the wrist member, the pivotal connection between the first armand the tool shaft defining a first pitch axis, and the pivotalconnection between the first arm and the wrist member defining a secondpitch axis; a first pitch pulley coaxial with the first pitch axis, anda second pitch pulley coaxial with the second pitch axis; a first pitchelongate element engaging the first and second pitch pulleys in a firstcircumferential orientation, the first pitch elongate element runningthrough the tool shaft; a second pitch elongate element engaging thefirst pitch pulley and the second pitch pulley in a secondcircumferential orientation opposite the first circumferentialorientation, the second pitch elongate element running through the toolshaft; the method further comprising: pulling the first pitch elongateelement to bend the instrument about the first and second pitch axes ina first direction, and pulling the second pitch elongate element to bendthe instrument about the first and second pitch axes in a seconddirection opposite the first direction.
 15. The method of claim 14,further comprising providing: first and second tangent surfaces attachedto the bottom of the base, the first and second tangent surfaces sharinga distal roll axis perpendicular to the pitch axis; first and seconddistal roll pulleys disposed on one side of the central extension, andthird and fourth distal roll pulleys disposed on an opposite side of thecentral extension; a first distal roll elongate element engaging thefirst tangent surface and the first and second distal roll pulleys, anend of the first distal roll elongate element running through the toolshaft; and a second distal roll elongate element engaging the secondtangent surface and the third and fourth distal roll pulleys, an end ofthe second distal roll elongate element running through the tool shaft;the method further comprising: pulling the first distal roll elongateelement to rotate the base in a first direction about a wrist axisextending from the proximal end of the wrist member to the distal end;and pulling the second distal roll elongate element to rotate the basein a second direction about the wrist axis opposite the first direction.